Peel the asparagus and cut the tips to approximately 10 cm. Retain the stems for alternative use. Cook the asparagus tips in boiling salted water for 4 to 5 minutes. Drain and refresh with cold water. Finely grate the orange zest and squeeze the juice. Whisk the juice in a small pan with ¾ of the olive oil, the vinegar, orange zest, salt and pepper. Brown the asparagus tips for 3 to 4 minutes under a hot grill or dry fry. In the remaining oil, fry the salmon portions for 3 to 4 minutes on each side. Season with salt and pepper. Gently heat the orange vinaigrette and whisk in the chopped coriander. Lay the salmon portions on the plates, arranging 3 asparagus tips on each portion. Pour over the warm vinaigrette and serve immediately.